An All-Digital Multichannel Narrow-Band FSK Data Receiver

The advent of large-scale integration has suggested new approaches to signal processing problems. In the data transmission field, for example, a complete modem can be built entirely of digital circuits. Not only is this approach technically feasible, but it is economically attractive, if the inherent speed of the digital devices is utilized by time-sharing the hardware among a large number of channels. This paper describes, an entirely digital multichannel narrow-band frequency-shift-keying data receiver. Input signals from each channel are converted to digital form and processed sequentially by a time-shared arithmetic umt composed of recursive digital filters. A prototype has been built and tested. If offers performance comparable to existing analog equivalents, while allowing extensive size and cost potential reductions.